Virtual characterization and macroscopic material modeling of a carbon fiber-reinforced PA6 UD composite

Abstract

Despite the increasing use of continuously fiber-reinforced composites with thermoplastic matrices in load-bearing structural applications, published research on their deformation behavior in general and their long-term behavior in particular is very limited. As a result, adequate material models to describe their time- and direction-dependent behavior on a macroscopic scale are lagging. The present study uses micromechanical representative volume element models and numerical homogenization techniques to analyze the material behavior of a carbon fiber-reinforced PA6 material as a function of load direction and time. The matrix is modeled as viscoelastic–viscoplastic. Based on the results of the representative volume element model, a homogenized macroscopic modeling approach is proposed. It is shown that the time dependency of the unidirectional composite is highly anisotropic. Plastic deformation occurs in the matrix, but may be neglected in the homogenized composite at laminate-relevant strain levels. The proposed homogenized orthotropic, nonlinear viscoelastic material model adequately captures the behavior of the heterogeneous unidirectional composite.